The lifting of a certain body mass, commonly called load, is typically carried out by mechanized equipment vertically suspending it, by means of hooks associated with flexible linear elements such as cables or chains, subsequently interconnected or attached to mechanical devices, placed at a upper position in relation to the load. These devices are called load lifting winches that retrieve and store cables or chains when hoisting a load.
The lifting winches, when intended to perform hoisting operations on large amplitude vertical paths, often include cylindrical cable drums that are also able to store the wire cables. They are also typically driven through the main axis of the cylindrical cable drum.
It's also possible to observe the existence of cylindrical drum winches with tangential drive to the drum using a spur gear transmission. Here the sprocket is mounted inside or outside the drum perimeter. The drive speed being constant and cylindrical geometry of the drum being also constant along its major axis, it translates into a constant cable winding speed as well. The load on the cable is subjected results from subdividing the total lifting load by introducing rope reeving sheaves both placed near the drum and hook, respectively sheaves top block and bottom block.
A cylindrical drum is featured by maximizing the cable storage along its perimeter. Given the cylindrical geometry of the drum, the winding length per drum rotation is constant along its length. Therefore, to increase the total winding length, it becomes necessary to increase the diameter of the cylindrical drum or, alternatively, increase the total cylindrical drum length or both. The engine torque at the main axis of the drum, required to lift the load increases proportionally to the diameter, increases proportionally as the drum diameter increase. This also means that the approach distance of the hook to the drum axis will have to proportionally increase as well.
The variable rotational speed in cylindrical drum winches is achieved by adding electromechanical variable drive systems or electronic devices such as adjustable AC or DC drives.